Dynamic Regressions with Variables Observed at Different Frequencies

We consider the problem of formulating and estimating dynamic regression models with variables observed at different frequencies. The strategy adopted is to define the dynamics of the model in terms of the highest available frequency, and to apply certain lag polynomials to transform the dynamics so that the model is expressed solely in terms of observed variables. A general solution is provided for models with monthly and quarterly observations. We also show how the methods can be extended to models with quarterly and annual observations, and models combining monthly and annual observations.

‘Good’ evidence for improved policy making: from hierarchies to appropriateness

Within the field of public health, and increasingly across other areas of social policy, there are widespread calls to increase or improve the use of evidence for policy making. Often these calls rest on an assumption that improved evidence utilisation will be a more efficient or effective means of achieving social goals. Yet, a clear elucidation of what can be considered ‘good evidence’ for policy use is rarely articulated. Many of the current discussions of best practice in the health policy sector derive from the evidence-based medicine (EBM) movement, embracing the ‘hierarchy of evidence’ in framing the selection of evidence – a hierarchy that places experimental trials as preeminent in terms of methodological quality. However, there are a number of difficulties associated with applying EBM methods of grading evidence onto policy making. Numerous public health authors have noted that the hierarchy of evidence is a judgement of quality specifically developed for measuring intervention effectiveness, and as such it cannot address other important health policy considerations such as affordability, salience, or public acceptability (Petticrew and Roberts, 2003). Social scientists and philosophers of knowledge have illustrated other problems in the direct application of the hierarchy of evidence to guide policy. Complex or structural interventions are often not conducive to experimental methods, and as such, a focus on evidence derived from randomised trials may shift policy attention away from broader structural issues (such as addressing the social determinants of health (Solar and Irwin, 2007)), to disease treatment or single element interventions. Social and behavioural interventions also present external validity problems to experimental methods and meta-analyses, as the mechanisms by which an intervention works in one social context may be very different or produce different results elsewhere (Cartwright, 2011). In these cases, policy makers may be better advised to look for evidence about the mechanism of effect, and evidence of local contextual features (Pawson et al., 2005). We argue that rather than adhering to a single hierarchy of evidence to judge what constitutes ‘good’ evidence for policy, it is more useful to examine evidence through the lens of appropriateness. It is important to utilise evidence to improve policy outcomes, yet the form of that evidence should vary depending on the multiple decision criteria at stake. Policy makers must therefore start by articulating their decision criteria in relation to a given problem or policy, so that the appropriate forms of evidence can be drawn on – from both epidemiological and clinical experiments (e.g. for questions of treatment effect), as well as from social scientific, social epidemiological, and multidisciplinary sources (e.g. for questions of complex causality, acceptability, human rights, etc.). Following this selection of types of evidence on the basis of appropriateness, the rigour and quality of the research can be assessed according to the evidentiary best practice standards of the discipline within which the evidence was produced. This approach speaks to calls to improve the use of evidence through ensuring rigour and methodological quality, yet recognises that good evidence is dictated by specific public health or social policy goals

Impact of Fluidic Chevrons on Jet Noise

The impact of alternating fluidic core chevrons on the production of jet noise is investigated. Core nozzles for a representative 1/9th scale, bypass ratio 5 model system were manufactured with slots cut near the trailing edges to allow for air injection into the core and fan streams. The injectors followed an alternating pattern around the nozzle perimeter so that the injection alternated between injection into the core stream and injection into the fan stream. For the takeoff condition and a forward flight Mach number of 0.10, the overall sound pressure levels at the peak jet noise angle decrease with increasing injection pressure. Sound pressure levels increase for observation angles less than 110o at higher injection pressures due to increases in high frequency noise. Greater increases in high frequency noise are observed when the number of injectors increases from 8 to 12. When the forward flight Mach number is increased to 0.28, jet noise reduction (relative to the baseline) is observed at aft angles for increasing injection pressure while significant increases in jet noise are observed at forward observation angles due to substantial acoustic radiation at high frequencies. A comparison between inflow and alternating injectors shows that, for equal mass injection rates, the inflow nozzle produces greater low frequency noise reduction (relative to the baseline) than the alternating injectors at 90o and aft observation angles and a forward flight Mach number of 0.28. Preliminary computational fluid dynamic simulations indicate that the spatial decay rate of the hot potential core flow is less for the inflow nozzle than for the alternating nozzles which indicates that gentle mixing may be preferred over sever mixing when fluidic chevrons are used for jet noise reduction

Activated prothrombin complex in the management of direct thrombin inhibitor-associated intracerebral haemorrhage.

Intracerebral haematoma expansion independently predicts poor functional outcome and mortality. Therefore, it is important to act quickly to arrest this expansion. Whilst a direct antidote to dabigatran remains in development, the use of factor VIII inhibitor bypassing activity may offer a practical strategy for arresting haemorrhage in individuals taking direct thrombin inhibitors.NRE is supported by a Research Training Fellowship from The Dunhill Medical Trust [grant number RTF44/0114].This is the author accepted manuscript. The final version is available from Oxford University Press at http://dx.doi.org/10.1093/qjmed/hcv219

Determining Alpha-Helix Correspondence for Protein Structure Prediction from Cryo-EM Density Maps, Master\u27s Thesis, May 2007

Determining protein structure is an important problem for structural biologists, which has received a significant amount of attention in the recent years. In this thesis, we describe a novel, shape-modeling approach as an intermediate step towards recovering 3D protein structures from volumetric images. The input to our method is a sequence of alpha-helices that make up a protein, and a low-resolution volumetric image of the protein where possible locations of alpha-helices have been detected. Our task is to identify the correspondence between the two sets of helices, which will shed light on how the protein folds in space. The central theme of our approach is to cast the correspondence problem as that of shape matching between the 3D volume and the 1D sequence. We model both the shapes as attributed relational graphs, and formulate a constrained inexact graph matching problem. To compute the matching, we developed an optimal algorithm based on the A*-search with several choices of heuristic functions. As demonstrated in a suite of real protein data, the shape-modeling approach is capable of correctly identifying helix correspondences in noise-abundant volumes with minimal or no user intervention

Investigation of shock waves in explosive blasts using fibre optic pressure sensors

The published version of this article may be accessed at the link below. Copyright @ IOP Publishing, 2006.We describe miniature all-optical pressure sensors, fabricated by wafer etching techniques, less than 1 mm(2) in overall cross-section with rise times in the mu s regime and pressure ranges typically 900 kPa (9 bar). Their performance is suitable for experimental studies of the pressure-time history for test models exposed to shocks initiated by an explosive charge. The small size and fast response of the sensors promises higher quality data than has been previously available from conventional electrical sensors, with potential improvements to numerical models of blast effects. Results from blast tests are presented in which up to six sensors were multiplexed, embedded within test models in a range of orientations relative to the shock front.Support from the UK Engineering&Physical Sciences Research Council and Dstl Fort Halstead through the MoD Joint Grants Scheme are acknowledged. WN MacPherson is supported by an EPSRC Advanced Research Fellowship

The effect of light intensity and temperature on berry growth and sugar accumulation in Vitis vinifera 'Shiraz' under vineyard conditions

Temperature and light are key climatic factors which affect grapevine physiology in the growing season. Our aim was to investigate the interactive effects of temperature and light intensity on reproductive growth responses of 'Shiraz' vines in vineyard conditions. Well-watered vines were covered with no shade, light, medium and heavy shade covers in a vineyard over three consecutive seasons. Several heat events, i.e., air temperatures exceeding 40 °C for several days, occurred in two of the seasons. Heavy shade reduced canopy temperatures by 3.2-6 °C in the cooler season and by 4-6 °C in the warmer seasons, relative to air temperature and compared with the open canopy. The onset of berry growth was delayed by the heavy shade but the rate of sugar accumulation was not affected. During the season with the most severe heat events, berry dry matter accumulation was significantly higher in the shaded treatments compared to the unshaded vines. The hypothesis was confirmed that medium and heavy shade conferred high levels of protection on the berry ripening process from high summer temperatures and the concurrent exposure to light intensities

Identification of Plant Growth-Promoting Rhizobacteria for the Development of Probiotic Consortia

  Soil infertility is one of the major challenges in agriculture. Although chemical fertilizers provide promising solution for crop growth in infertile soil, excessive application cause negative impacts on the natural systems such as soil and water. Moreover, these fertilizers can be converted into insoluble forms soon after application which often result in increasing the application frequency and the quantity. Hence, for decades plant growth-promoting rhizobacteria (PGPR) have been considered as an environmentally friendly alternative for chemical fertilizers. In this context, the present study was focused on the identification of candidate PGPRs for the development of probiotic packages for chilli (Capsicum annuum L.) which is one of the most widely grown and highly demanding vegetable crops in Sri Lanka. Rhizobacteria were isolated from the roots of healthy, young chilli plants grown in Angunakolapelessa, Sri Lanka and their rhizosphere soil. In total, 75 morphologically distinct strains were isolated, and they were inoculated into different nutrient media to screen their ability to solubilize insoluble mineral nutrient sources. Those media were National-Botanical-Research-Institute's phosphate agar [NBRIP-agar] with Ca3(PO4)2 as the P source, modified-Aleksandrov-agar containing mica as the K source and zinc-solubilizing-agar containing ZnCO3 as the Zn source. Further, bacteria were screened for N fixation in the nitrogen- fixing-bacteria (NfB) medium. Sixteen P-solubilizing-bacteria (PSB), 4 K-solubilizing-bacteria (KSB), 15 Zn-solubilizing-bacteria (ZnSB) and 10 N-fixing strains were identified. We noticed that all KSB strains also have the capacity to solubilize Ca3(PO4)2. All PSB strains, except CSTM10, can solubilize ZnCO3. The phosphate solubilizing index (PSI) was calculated to rank the P-solubilizing efficiency (PSE) of PSB. The highest PSI was found in CSTM40 and CSTM6. We further screened all mineral-solubilizing strains for the indole-3-acidic acid (IAA) production which is a PGP hormone. Cultures were induced for IAA production by supplementing the medium with 0.2% (w/v) tryptophan and IAA concentration was determined using the Salkowski's method. Nine strains were capable of producing IAA. The CSTM6 and CSTM21 showed the highest IAA production of 181.94 and 178.59 mg/L respectively. In conclusion, bacterial strains, CSTM6, CSTM14, CSTM21, CSTM24, CSTM40, CMTM1, CMTM2 and CSTM10 showed multiple PGP characteristics and they were selected as candidates for the developing probiotic consortia. They can be viewed as promising strains in sustainable agriculture since they perhaps can enhance the availability of mineral nutrients in soil and promote plant growth.   Keywords: Biofertilizer, Capsicum annuum, Plant growth-promoting rhizobacteria   Financial assistance from Indo-Sri Lanka Joint Research Programme 2019 funded by the State Ministry of Skill Development, Vocational Education, Research and Innovation, Sri Lanka is acknowledged. &nbsp

The International-Trade Network: Gravity Equations and Topological Properties

This paper begins to explore the determinants of the topological properties of the international - trade network (ITN). We fit bilateral-trade flows using a standard gravity equation to build a "residual" ITN where trade-link weights are depurated from geographical distance, size, border effects, trade agreements, and so on. We then compare the topological properties of the original and residual ITNs. We find that the residual ITN displays, unlike the original one, marked signatures of a complex system, and is characterized by a very different topological architecture. Whereas the original ITN is geographically clustered and organized around a few large-sized hubs, the residual ITN displays many small-sized but trade-oriented countries that, independently of their geographical position, either play the role of local hubs or attract large and rich countries in relatively complex trade-interaction patterns